Hydraulic actuator



J. MERCIER HYDRAULIC ACTUATOR Filed June 50, 1959 Nov. 21, 1961v JEAN MERUER By en, @M M ATTORNEYS United btates 3,009,322 HYDRAULEC ACTUATR Jean Mercier, 1185 Park Ave., New York, NSY. Filed .lune 30, 1959, Ser. No. 823,947 9 Claims. (Cl. nti-52) This invention relates to the art of hydraulic actuators more particularly of the telescopic type.

It is among the objects of the invention to provide a hydraulic actuator which is relatively simple in construction, dependable in operation and which has a plurality of moving elements that can be independently controlled by a plurality of uid pressure applied thereto.

According to the invention, the actuator comprises at least two separate chambers, one being slidably mounted in the other and defining a plunger which may be actuated by the introduction of lluid under pressure in said other chamber. A second plunger is slidably mounted in said first chamber and is also actuated by fluid under pressure forced into said first chamber, the two chambers and the second plunger being axially aligned and forming a telescopic arrangement.

Another object of the invention is to provide a hydraulic system utilizing a plurality of actuators of the above type to provide for angular displacement of a member about an axis.

According to the invention these objects are accomplished by the arrangement and combination of elements hereinafter described and more particularly recited in the claims.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention.

FIG. 1 is a longitudinal sectional view of the telescopic actuator according to the invention, and

FIG. 2 and 3 are diagrammatic views of systems utilizing telescopic actuators.

Referring now to` the drawings the actuator or jack shown in FIG. 1, comprises a cylinder 1 closed at one end as at 1 and having a cap at its other end through which slidably extends a smaller diameter cylinder 2. The end 2 of cylinder 2 in cylinder lis closed and the other end of cylinder 2 has a cap through which slidably extends a tubular member 3. Appropriate gaskets 4 and 5 provide a seal between cylinders 1 and 2 and between cylinder 2 and tubular member 3.

The cylinder 2 thus forms a plunger in cylinder 1 and the tubular member 3 forms a plunger in cylinder 2.

The space between the cylinder 1 and the plunger or cylinder 2 defines a chamber 6 into which iluid under pressure may be admitted through a port 7 located in the Wall of cylinder 1. The space between the cylinder 2 and the tubular member 3 defines a chamber 8, which is independent of chamber 6 and into which fluid under pressure may be admitted through a port 9 leading into the bore of tubular member 3.

Flow of fluid under pressure into chamber 6 tends to cause outward longitudinal displacement of cylinders 1 and 2 and flow of fluid under pressure into chamber 3 tends to cause outward longitudinal displacement of cylinder 2 and tubular member 3.

Assuming that the cylinder 1 is secured in fixed position, then fluid under pressure forced into chamber 8 would `cause elongation of the assembly comprising cylinder 2 and member 3, While a fluid under pressure forced into the chamber 6 would force the assembly 2, 3 outwardly from cylinder 1. Such movements would occur regardless of the values of the two pressures.

A telescope apparatus has therefore been provided which is of extreme simplicity. The two chambers 6 and 8 of the jack operate independently of each other and can 3,009,322 Patented Nov. 21, 1961 be controlled at will. If, for example, the two chambers 6 and 8 are supplied successively or simultaneously with substantially equal pressures, there will exist in the chamber 8 a pressure suiilcient to elongate the assembly 2-3 with a given force and in chamber 6 a pressure capable of displacing the said assembly 2-3` toward a position corresponding to the complete extension of the apparatus, with a force greater than that bringing about the elongation of the said assembly 2-3 due to the `fact that the diameter of the cylinder 2 is -greater than that of the member 3.

The telescopic apparatus according to the invention finds a desirable application in hydraulic systems and particularly those operating on a ship rudder.

Referring to HG. 2, a rudder shaft 10 is provided on which the swing bar 11 of the rudder is mounted in manner to present two arms 12 and 13 of different lengths. The hydraulic control system for the rudder comprises a hydraulic motor C which has a cylinder 14 in which a piston 15 is slidably mounted, said piston being connected to one end of a piston rod 16, the other end of which is connected at 17 to the end of the arm 13 of the swing bar 11. Two telescopic actuators or jacks A and B of the type shown in FIG. l are provided. The plunger 3a of jack A is connected at 18 to the end of the arm 12 of bar 11, which is of shorter length, and the plunger 3b o-f the jack B is connected to the arm 13, which is of greater length, at a point 19 between the shaft 10 and the connected point 17 `of the piston rod 16 of the motor C. The distances between the shaft 10 and each of the pivotal points 18 and 19` are illustratively selected in manner such as to lbear a l to 2 ratio.

The cylinder 1a of jack A is connected at 20 to one of the ends of a rod 21 mounted on a xed pivot 22, the other end of the rod being connected at 23 to the cylinder 1b of jack B. The distance between the points of connection 2% and 23 corresponds to the distance between the points of connections 18 and 19 of the swing bar 11, and the distance between the point of connection 21) and the pivot 22 corresponds to the distance between the shaft 10 and the point of connection 13 of the swing bar. The movement in each direction of the rod 21 around the pivot 22 and consequently the course of each of the cylinders 1a and 1b of the jacks, is limited by the stops 24 and 25.

The movable element 26 of a distributor 27 is pivotally connected as at 28 to rod 21, so that upon displacement in one direction or the other of rod 21 around pivot 22, liquid under pressure would be directed from a supply P through one or the other of lines 29 and 30 to cylinder 14 of motor C.

The liquid under pressure admitted into chambers 8a and 8b of the jacks A, B comes from a pump 31 connected by a line 32 to the reservoir 33l and the liquid under pressure admitted into chambers 6a: and 6b of the jacks comes from a pump 34 connected by a line 35 to the reservoir 33.

More specifically, the outlet of pump 31 is connected by line 36 to a three-way distributor 42 and by line 37 to port 9a of jack A. In addition one of the ports of the distributor 42 is connected by line 38 to port 9b of jack B and the other port is connected by line 45 to reservoir 33.

Similarly, the outlet of the pump 34 is connected by line 39 to a three-way distributor 43 and by line 40 to port 7a of jack A. In addition, one of the ports of the distributor 43 is connected by line 41 to port 7b of jack B and the other port is connected by line 45 to reservoir 33.

By means of the distributor, the chambers 8b and 6b of jack B can be connected either to pumps 31 or 34 respectively, or to the reservoir 33. The valves 46, 47 in lines 36, 39 control communication between pump 31 and the chamber Sa and between the pump 34 and the chamber 6a of the jack A. Finally, the pressure accumulators 48, 49 connected to the lines 36, 39 constitute a reservoir of energy in case of need.

It is noted that the swing bar 11 is blocked in one of its positions by the liquid in the motor C as long as the distributor 27 remains closed.

The operation of the hydraulic system shown in FlG. 2 is as follows:

With the distributor 43 and the valve 47 in a position in which the chambers 6a and 6b, of the jacks A and B are connected to reservoir 33, the valve 46 is opened and the distributor 42 positioned so that the fluid from pump 31 will ow through line 36 into lines 37 and 38, into the chamber 8a of jack A and into the chamber 8b of jack B. As a result the plungers 2a and 2b, respectively, will be driven toward the bottoms of cylinders 1a and 1b of the jacks A and B, the uid in the chambers 6a and 6b flowing into reservoir 33. The swing bar 11 being blocked by the liquid imprisoned in motor C, it is easy to understand that the fluid under pressure admitted into chambers 8a and 8b tends to displace the cylinders 1a and 1b toward the right.

Supposing, moreover, that there was chosen for the lever arms of the swing bar 11 and the rod 21 a ratio of 1:2, and that each of the pressure sources 31 or 4S and 34 or 49 is capable of discharging liquid at a pressure of 30() kg., if it is desired to pivot the swing bar 11 in one direction or the other, it is suiiicient to control the pressure admitted to the chamber 8b by the distributor 42, in such manner that this pressure attains a Value either below or above equilibrium pressure, which is about 150 kg. in the example selected. The constant pressure of 300 kg. admitted into chamber 8a of jack A, brings about the rocking of the rod 21 in overcoming the pressure in chamber 8b of jack B when that pressure is below 150 kg., and a pressure of more than 150 kg. in the chamber 8b brings about the rocking of the rod 21 in overcoming the constant pressure 300 kg. in the chamber Sa of the jack B, the rod 21 remaining motionless only if the pressure in the chamber 8b is approximately half the pressure in the chamber Sa.

With this description, if it is desired to pivot the swing bar 11 in a clockwise direction, for example, the distributor 42 is set so that the pressure admitted to the chamber 8b of jack B exceeds the equilibrium value. As a result a. displacement is brought about of the cylinder 1b toward the right in the direction of the stop 25, and through the rod 21 the cylinder 1a is correspondingly displaced but in the opposite direction. The rocking of the rod 21, transmitted through the control rod 26 of the distributor 27, provides flow of liquid under pressure through conduit 29 leading to cylinder 14 of the motor C and connects conduit 30 with the reservoir.

The pressure of liquid against the right wall of piston 15 assures the pivotal movement of the swing arm 11 in the desired clockwise direction, the effort of the piston 15 upon the swing arm 11 against the action of the external source or the resistance encountered by the movement of the rudder being assisted by the pressure admitted into chamber 8b of jack B which tends to extend plunger 3b of that jack to react against arm 11.

As soon as the swing arm 11 has attained the desired position, the distributor 42 is actuated to cut off communication between the chamber 8b of jack B and the pressure source 31, 48, thus stopping the extension of that jack. However, the piston 15 of the motor C continues to rotate arm 11 around the axis 10 ina clockwise direction, causing a displacement of the connecting point 20 toward the right, and through the rod 21, causing a displacement of the connection point 23 toward the left. The rocking of the rod 21 brings about a displacement of the rod 26 now in the direction of closure of distributor 27 in manner to cut off flow of fluid under pressure to the motor C thereby to retain the swing arm 11 in its new position when the rod 21 is restored to its initial position shown in FIG. 2.

To control a rotary movement of swing arm 11 in a counter-clockwise direction, the distributor 42 is actuated in manner to diminish the pressure in chamber 8b, thus bringing about an expansion of jack A and a retraction of jack B.

1f, for any reason whatsoever, the chambers 8a and 8b are not supplied with pressure, it is sufficient in order to restore the normal operations described, to so actuate the distributor 42 that it connects the lines 37 and 38 to the reservoir 33; to open the valve 47 in order to place the chamber 6a of jack A in communication with the sources 34, 49 and to actuate the distributor 43 so that the pressure conveyed from the sources 34, 49 by line 41 to the chamber 6b of jack B is in equilibrium with the pressure in chamber 6a of jack A.

The control of the position of swing arm 11 when use is made of the pressure sources 34-49 occurs in the same manner as the normal control in which there is utilized the pressure sources 31, 48, the only difference residing in the fact that the pressures admitted originating in the chambers 6a and 6b displace plungers 2a and 2b of jacks A and B against the plungers 3a and 3b (assuming that the latter are in discharge relation). The cylinders thereupon are displaced in one direction or the other as previously described when there is admitted at 6b a pressure above or below half that which exists at 6a. 'It is to be noted, however, that the pressure exerted against plungers 2a and 2b is evidently greater than that which could be exerted against plungers 3a and 3b in normal operation from the pressure sources 31-48 (assuming that the two sources are under the same pressure).

In the embodiment in FIG. 3 the jacks A and B are arranged on opposed sides of swing bar 11, the smaller diameter plungers of the jacks being connected to the swing bar 11 at the same point 19a.

A pump 51 is connected by conduits 52 and 53 to the smaller diameter plungers and a pump 54 is connected by conduits 55 and 56 to the cylinders of jack A and B, in manner such that the liquid under pressure for operating the jacks circulates between the jacks in a closed circuit across the pumps 51 and 54. A valve 57 interposed in a conduit 58 permits forming a bypass between the conduits 52 and 53 and a valve 59 interposed in conduit 60 permits forming a bypass between the conduits 55 and 56 in manner to put the pumps 51 and 55 in hydraulic short circuit.

The cylinder of jack A is connected at 61 to an arm 62 which may oscillate around a fixed pivot 61, and the cylinder of jack B is connected at 64 to an arm 65 which may oscillate around a fixed pivot 66, a rod 67 connected at 68 and 69 to the free end of the arms 62 and 65 maintaining the latter in parallelism.

A rod 26a connected at 70 to the arm 62 controls the movable member of the distributor 27 to control the low of liquid under pressure to the motor C for operation thereof.

A chain transmission system or the like 71 connects the two pumps 51 and 54 to a rotatable member 72 in manner such that rotary movement of this member brings about a simultaneous rotation of the two pumps. The hydraulic circuits being previously charged with liquid and the two valves 57 and 59 closed, pumps 51 and 54 replenish one of the jacks A and B with as much liquid as they have drawn from the other.

Thus, when the rotary member 72 is turned in a predetermined direction, the valve 59 being opened to place the pump 54 in hydraulic short circuit, the pump 51 operated by the rotary member 72 forces liquid under pressure by way of conduit 52 toward the jack A while drawing liquid from the jack B by way of conduit 53. Thus jack A will extend to the left and through the arm 62, the rod 67 and the arm 65, the jack B will retract t0 the left. The pivoting of the arm 62 in a clockwise direction will, through the rod 26a, actuate the distributor 27 to provide fluid under pressure to motor C thereby pivoting the bar 11, the distributor 27 being controlled in such fashion that the pivoting of the swing bar 11 occurs in a direction opposed to that of the pivoting of arms 62 and 65.

When rotation of the pump 51 has been stopped, the `distance between the points 61 and 64 becomes fixed and the distributor 27 actuated the motor C will continue to displace the swing bar 11 in a counter-clockwise direction, the effect of which is to cause pivoting of the arm -62 in the same direction, to restore the distributor 27 to its original position to establish the new position of swing bar 11.

The same operation but in opposed direction occurs by turning the rotary member 72 in `direction opposed to the foregoing.

In case of breakdown of the circuits 51, 52, 53, circuits 54, 55, 56 may be placed into the operation by closing the Valve 59, thus permitting the pump 54 to reestablish the operation described. lThe pressure chambers provided in the cylinders of jacks A and B to operate with the circuits 54, 55, 56 now come into place, thus assuring the transmission of pressure developed by the pump 54 to the bar 11 with a force greater than that exerted upon the swing bar by the jacks A and B in the course of normal operations, that force being such that it is capable of displacing the bar in case of failure of the motor C.

'It is apparent in view of the foregoing, that as the plungers 3a and 3b are of relatively small active area, when actuated they will have little direct effect in moving the swing bar, but will actuate the distributor controlling the motor for movement of the swing bar.

However, when the plungers 2a and 2b are actuated, due to their relatively large active area, they will both actuate the distributor controlling the motor and also have a substantial direct effect in moving said swing bar.

As many changes could be made in the above constructions and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

'Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A hydraulic system comprising a first and second source of fluid under pressure, a pivotally mounted control member, a pair of fluid controlled actuators each comprising a pair of cylinders, one slidably mounted in the other and defining a plunger, and a second plunger slidably mounted in said first plunger, means to effect fiow of fluid under pressure from one of said sources into one of the cylinders of each actuator for actuation of the plungers thereof, means to provide discharge of fluid from the other cylinder of each actuator, a fluid motor having a pair of ports, said fluid motor being operatively connected to said control member to rotate the latter in either direction about its pivot, a uid distributor adapted to connect the ports of said iiuid motor to a source of fluid under pressure and to a return for such fluid, respectively, control means for said distributor, said actuators being operatively connected to said control member and said control means, whereby upon actuation of the plungers of said actuators and movement of said control means for said distributor the motor will be actuated to pivot said control member in either direction.

2. The combination set forth in claim l in which said second plungers are respectively pivotally connected to said control member on opposed sides of the pivot thereof, a rod is provided pivotally mounted between its end, the outer ends of the other cylinders being pivotally connected to the ends of Asaid rod, said motor being operatively connected to said control member outwardly of the connection of the plunger thereto.

3. The combination set forth in claim 2 in which the distance between the axis of the control member and the connection of the plungers thereto is equal to the distance between the axis of said rod and the connection of the cylinders thereto.

4. 'The combination set forth in claim 2 in which one of said plungers is connected to the control member at a distance from the axis thereof greater than the other of said plungers.

5. The combination set for in claim 1 in which a reservoir for return of fluid from said first and second sources is provided, a distributor is connected between said first source of fluid under pressure and the first cylinder of one of said actuators and means connecting said first source of liuid under pressure to the first cylinder of the other of said actuators and means to connect said second cylinder of each of said actuators to said reservoir.

6. The combination set forth in claim 1 in which a reservoir is provided for return of fluid from said first and second sources, a pair of distributors is provided connected respectfully between said first and second sources of fluid under pressure and the first and second cylinders of one of said actuators, means to connect the first and second sources o-f fluid under pressure to the first and second cylinder of the other of said actuators, and means to connect one of said cylinders of each of said actuators to said reservoir `when the other cylinder of each of said actuators is connected to one of said first and second sources of fluid under pressure.

7. The combination set forth in claim l in which said second plungers are pivotally connected to said control member on one side of the pivot thereof, a pair of levers each pivotally mounted at one end and positioned respectively on each side of said control member, the ends of said other cylinder of each of said actuators being pivotally connected to said levers, a rod pivotally connected at its ends to the free end of said levers, said distributors being operatively connected to one of said levers to be actuated thereby.

8. The combination set forth in claim 7 in which a pump is provided connected in series between said first cylinders of said actuators and a second pump is provided connected in series between the second cylinders of said actuators, means being provided to actuate said pumps, said pumps comprising said first and second sources of fluid under pressure.

9. The combination set forth in claim l in which the effective area of said second plunger is relatively small as compared to the effective area of said first plunger, said first plungers: when actuated having little direct effect in pivoting said control member, said second plungers when actuated having a substantial direct effect in pivoting said control member.

References Cited in the file of this patent UNITED STATES PATENTS 1,465,278 Melchior Aug. 21, 1923 2,095,051 Bristol et al. Oct. 5, 1937 2,763,990 Mercier Sept. 25, 1956 

